Electric circuit breaker



Oct. 25, 1938. s. DEWAR ELECTRIC CIRCUIT BREAKER Filed Aug. 24, 1957 Inventor: George Dewar,

cfflMZ ttorney 1 tent f j J; H $134,549 W H omcmrprtmmrin V 5 essenc s; is'tretford, Manchester," England, l

assignor to: General Electric Company, a; corporation of New York Applicat ion August 24, 1931, SeriaiNo. 30,691

, ,x r syatvettsa genesis sie e- 6 circuit b eakers ofthekind having trippablemeansby which 3 the circuit breaker is maintained; closed, and by isusuallyof the circuit opened again inbasethe breaker is closed o ashort circuit. The trippable means the kind providing what is commonly termed a trip-tree mechanism, namely a mechamar ne cb t i ywb aged'by arcing if the closure is notcompleted within a certain time after the ,contacts touch,

1 or, in other words, if duringthe finalclo slng action the'circuit breaker fails to close thecontacts at a predetermined speed. 3 I Thus fwhen the, moviingcontactinitiallv engagesythe (ac-operating r contact saidmoving,oontactmayhesitate or even be reversed in its movement,.duefto the 'electro magnetic forces set up at-said contacts, Devices have therefore been proposed by which' backward .rnovement of the moving contact,or lagkof the moving contact, duringtheclosing movement,"

)the circuit breaker is immediately tripped nism arrangedsoastobe trippable at any-tune 1 "jyinthe closing operation of the eircuit breaker. "It 7 r has been found accordingto' the invention.

In Great Britain September 15, 1936,

'1 Claims. ((01. 200-153) connecting thetsaamg ieverand 'tne'aqtuatm lever, and a linkbetween the operating lever and therack-bar 'for, actuating the trip lever so as relative movement between said operating lever and link, thus releasing ,thetripfree mechanism. In order that the invention may be clearlyun-q yderstood' it will now .be described with reference to disengage the actuating lever in response to l l to the accompanying drawing, the singlefljgure of which is an elevational view showing'bvway of example one: form, of circuit breaker constructed The' circuit breaker shown isflof the convert} tional double -break'type having a bridge! carrying the movable contacts connected to a lever 2 breakerpel'ement or lever 2 is connectedthrough will cause the tripping mechanism to operate and the circuit breaker immediately to Opem The' objector the presentfinvention is thepro'visionl of an improved mechanismof thiskindywhich shall be, simpleand certain in its operation. According to theinvention'theoperating lever v orthandle of the circu t-b s which may be suitably operated"byt electric means ortman ually during closure of the breaker, is; connectedto'an actuating lever;through; trip-free mechanismand is further connected with energy-storing means;

such as a; flywheel, ,which is therebv causedvto rotate duringthe operation of-closing inlsuchra wmannerthat if the speed ormovementof the op-,

l eratingdever, is reduced relativelyttothat of the actuating-lever the continuedrotation of the flymatter alink 4 with an actuating lever- 5 pivoted at a fixed pointt coaxially with an operating element such as a lever- 1 which, asshowrnis provided with a handle for manualoperation. -The free a 1 that is pivotedon arlxedaxis 3. The movable I arm of the actuating lever} has acatch 8 with which engages under normal conditions a roller 9lcarried by a trip leverllp, pivotedat H to the q operating lever I. Also pivoted tothe operating lever I coaxially with the trip lever In is allink ll to the endof whicharack-bar l3 isconnected. The link; I'Z 'has a projection l4 fora purpose hereascribed. M15, is movable energy-stop ing: means such as a flywheel corinected through u hion tld ve we eik tb a sprin 11 on other cushioning connection and, carrying a pin:

l, and the rack-bar i3 is guided in engagement with j wheel-, duegto its inertia; will release, thetrip+free v mechanisrn iso as permit ath circnit breaker to' 1' I 1M w In carrying out, the iinventionxthe operatingw lever may beconnected withthe flywheel through as it ,1 continued movement of the rack-bar under the rotationfof the flywheel when the'speed of movement of the operating lever is reduced a predeter-- mined amount relative to its initial movement a, link"; and rack-and-pinion:tmovement and the causes a movement of the link relative to the operating" lever, which movement releases the trip free mechanism.

to asuitable level. J

;--!I'he operation of the device, isasfollows: Thethe pinion 18 by the roller l5 which' ro'tates on a pivot I supported in s a tixed bracket 20. The. operati g layer has, aprojection .2l adaptedto engage with the link 12 'as'shown. The circuitbreaker, the fixed contacts of which are shown at 23, is contained in a tank 22 which is filled withliquid drawing shows thecircult breaker insthe open position. The roller 9 of thetr-ip lever in this positlon is in engagement with the catch 8; of the vactuating lever 5' andif the operating lever I is moved downwards tothe position: shown 81721 in,

, to the position indicated in broken linesl', thus ,The. trip-freesmechanism mav"comprise any suitable earrangement such as :a .trip ,leverg pivoteti. to the operating a lever for detachably interraising the bridge piece I to its upper position in broken lines the actuating lever 5 will be rotated inthe clockwise direction and through the link 4 will rotate the lever 2 'in the clockwise direction which its contacts engage withltheflfixed conftacts 23. During this movement the stop 2| carried on the operatinglever I engaging with the link 12 forces the rack-bar ll downwards so that the flywheel I5 is caused to rotate in the clockwise direction. If during this movement the motion of the operating lever is checked or reduced in speed sufllciently in excess of the normal deceleration consequent upon the meeting and final closure ofthe circuit breaker contacts the flywheel |5 due to its inertia will continue to maintain its speed of rotation and will move the rackbar 13 downwards relatively to the operating'handle 1. This will cause rotation of the link I 2 on its pivot to such an extent that the projection M will engage with .the trip lever l0 and rotate the same clockwise about its pivot so as to release the roller 9 from the catch '8 on the actuating lever 5. Accordingly the lever 5 is free to rotate on its pivot in the counter-clockwise direction independently of lever I thereby permitting the circuit breaker to open in the usual way.

A trip coil 24 may be provided acting on a plunger 25 which can operate a pivoted trip lever 26' to cause it to engage with the trip arm l0 when the operating lever l is in its lowest or near its lowest position so as to cause the roller 9 to release the actuating lever 5 and open the circuit breaker when required and provide tripfree operation. Other forms of electromagnetically or manually operated tripping apparatus obviously may be employed with the circuit breaker operating mechanism shown.

' I claim:--

1. Electric circuit breaker nism comprising a movable ment, an operating element and trip-free structure interconnecting'said elements including a tripping device, energy-storing means movable operating mechain accordance with the circuit-closing movement of said operating element at a speed corresponding to that of said element, and means operatively relating said energy-storing means to said tripping device for causing actuation thereof in response to predetermined reduction in the closing speed of said operating element.

'2z'Electric circuit breaker operating mecha nism. comprising a movable breaker element, an operating element, and trip-free structure including a tripping device interconnecting said elements, and means having appreciable mass related to said operating element so as to move at a speed corresponding tothat of said operating element during the normal circuit-closing operation, said means also coacting with said tripping device so that the inertia of said mass is effective to actuate said tripping device in response to predeterminedreduction in the closing speed of said operating element.

3. Electric circuit breaker operating'meohanism comprising a movable breaker element, an operating element, a trip-free linkage interconmeeting-said elements including a latch for holding said linkage in thrust-transmitting position, a rotatable member having appreciable mass, and means interconnecting said operating element and rotatable member for causing rotation thereof at a speed corresponding to the circuit-closing speed of said element, said interconnecting means being also operatively related to said latch for causing tripping thereof, the inertia of said rocircuit breaker eletating mass in response to predetermined reduction in the closing speed of said operating element ing fly-wheel for actuating said latch to the tripping position in response to predetermined reduction in the closing speedgof said operating element.

5. Electric circuit breaker operating mechanism, comprising a movable breaker element, an operating element, trip-free structure including a latch interconnecting said elements, a rotatable member having appreciable mass and means including a rack and pinion device for interconnecting said operating element and rotatable member for rotating said member at a speed corresponding to the circuit-closing speed of said element, and means relating said rack and pinion connection to said latch for causing tripping thereof due to the inertia effect of said rotating member when'the speed of said operating element is retarded a predetermined extent.

6. Electric circuit breaker operating mechanism comprising a movable breaker element, an operating element, trip-free structure including a latch interconnecting said elements, a fiy-wheel having a resilient connection with the operating shaft thereof, means including a rack and pinion for interconnecting said shaft to said operatingelement, said rack being related to said latch so that predetermined movement thereof causes tripping of said latch, said operating element causing rotation of said flyi-wheel through said rack and pinion at a speed corresponding to the circuit-closing speed of said elementand the inertia of said fly-wheel causing relative movement of said rack with respect to said element to cause tripping of said latch in response to predetermined reduction in the closing speed of said operating element;

7. Electric circuit breaker operating mechanism comprising a movable breaker element, a pivoted operating element, trip-free linkage interconnecting said elements, a latch pivotally mounted-on said operating element for holding said linkage in thrust-transmitting position, a rotating member havingan appreciable mass, a gear rack pivotally connected at one end to said operating lever and at its other end through a coacting pinion to said rotating member, said operating element causing rotation of said member at a speed corresponding to thecircuit-closing speed of said element through said rack and pinion, and means interrelating said rack and latch whereby the inertia of said rotatable member causes relative movement of said rack in the reverse direction upon predetermined retardation of said operating element to cause tripping of said latch. Y

GEORGE DEWAR. 

